1. Field of Invention
The present invention relates to a separation membrane having antibiotic and hydrophilic properties for water treatment and a preparation method thereof.
2. Background of Invention
The existing hollow fiber preparation method includes the steps of preparing a film-forming solution by dissolving a polymer material in a solvent, and preparing a porous separation membrane by precipitating the same in a non-solvent to induce the phase transition. In order for a hollow fiber membrane to be usefully used for water treatment, and the like, characteristics such as antimicrobial properties, high rejection rate and water permeability, stain resistance, and mechanical strength which may withstand the working pressure, are required. In general, for the preparation of a hollow fiber membrane including an ultra filtration membrane, polysulfone, polyethersulfone (PES), polyacrylonitrile or polyvinylidene fluoride (PVDF) and the like are usually used. An ultra filtration membrane prepared by using these materials satisfies the rejection rate as the ultra filtration membrane, but has problems in water permeability and stain resistance characteristics due to low hydrophilicity of the polymer material. Further, since a filtration membrane for water treatment is continuously brought into contact with water, and thus has a problem in that bacteria are growing in the filtration membrane prepared by using a polymer material, a process of periodically subjecting the filtration membrane to a chemical treatment during the use thereof needs to be performed. In order to prevent or suppress bacteria from growing in the filtration membrane, it is required to impart antimicrobial properties to the filtration membrane. In order to increase the water permeability of the ultra filtration membrane, the ultra filtration membrane is prepared by adding a water-soluble polymer polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), and the like to a casting solution. However, the thus prepared ultra filtration membrane has problems in that a water-soluble polymer added during the water treatment is dissolved in water, is removed from the ultra filtration membrane, and thus gradually loses hydrophilicity, and as a result, water permeability, rejection rate, and mechanical strength are gradually reduced as the use time elapses.
In order to solve the aforementioned problems of the existing filtration membrane, (1) a method for imparting hydrophilicity by introducing silver nanoparticles into a casting solution (the official gazette of Korean Patent No. 10-1139145), (2) a method for imparting hydrophilicity by subjecting an ultra filtration membrane prepared to plasma treatment (the official gazette of Korean Patent Application Laid-Open No. 10-2008-0061049), (3) a method for imparting hydrophilicity by introducing carbon nanotubes into a casting solution (the official gazette of Korean Patent Application Laid-Open No. 2012-0076914), and (4) a method for preparing an ultra filtration membrane by using a polyacrylonitrile polymer (the official gazette of Korean Patent Publication No. 10-1995-004917), and the like have been developed. From these methods, mechanical strength and hydrophilicity of the ultra filtration membrane have been somewhat improved by introducing a filler, but there is a disadvantage in that it is difficult to expect antimicrobial properties and a continuous improvement in hydrophilicity from the ultra filtration membrane. In addition, hydrophilicity has been improved, and stain resistance and chemical resistance have been somewhat improved by a method for coating an ultra filtration membrane with titania (the official gazette of Korean Patent No. 10-0543573) or a method for preparing an ultra filtration membrane by adding titania to a casting solution (Korean Patent No. 10-0536643), and the like, but it is difficult to expect antimicrobial properties and high water permeability and solute rejection rate.
Throughout the present specification, a number of papers and patent documents are referenced, and citations thereof are indicated. The invention of each of the cited documents is incorporated herein by reference in its entirety to describe the level of the technical field to which the present invention pertains and the content of the present invention more apparently.